Today I was involved in a project of the coast of San Miguel Island which is part of the Channel Islands.
View Larger MapWe were diving off the northwest coast south of the large cove. We had ambitions to lay grids, do transects, the works -- all in the name of archaeology. People do this on land all the time. How hard can it be underwater?
Very. Try doing tasks with people where you can only communicate with hand gestures. Some people might be more adept at charades than others, which can be a plus, but this is still a major impediment.
Things like rope or plastic have a tendency to float and will get you entangled as soon as you submerge yourself. Other objects are bulky and cumbersome to lug around. I do have pockets, but they are on the sides of my thighs and aren't easily accessible as your maneuverability is limited so that for the most part you have to know where to feel for things on your person because you can't see them. So now there's a dilemma because in diving, hands-free is the way to be. While down, we attempted a survey with line, where we tried to run toward shore along an east-west coordinate. I think the job would have been a lot easier without the rope. Often times we were tugging on it to get it around rocks or stopping to untangle the mass it created from itself. I think what just needs to be done in a reconnaissance situation such as this is just what you do on land. You lay tracks with a GPS, noting what areas you have covered.
We thought ahead and brought screens and dust pans that might help in fanning sand away, but we never really got to the point where we were certain we should "dig" in a certain location.
Our initial dive was at 40 feet. There was nothing here but sand. Sea life was rather sparse as well. Heading further toward shore around 30 feet, rocks began to appear. This is where the bull kelp was growing. Among these rocks were thousands of sea urchins along with rock fish and starfish. Urchins feed on the kelp so this location makes sense. Sea mammals keep these spiny creatures in check as they dine on them. Among the crevices and cracks where the sea urchins called their home, the potential for cultural remains increased. Along the southern shore of the island a large mortar (about 9" in diameter) was found underwater. The depth may have been something similar to what we ended up diving at. By the time we realized this however, Jack's ear had been bothering him to the point where he no longer felt comfortable diving. I apparently have a rather leaky dry suit which is probably my fault, spawning from the time I dove without a weight belt. Instead I packed the weight in those pockets along my thigh. It was nearly 25 pounds between the two, and I think it did some damage to my suit. Upon getting out of my dry suit everything I was wearing was wet. It wasn't sopping, but definitely wet.
Tricia got a dive in and may have been down for one more, but our turn time was quickly approaching to head back to the mainland before the weather started to pick up, as was the forecast. Oddly enough, the ride back was silky smooth. The way out had swells up to 6 feet or more where every now and then the boat would get tossed up by a swell and come crashing down to the lowered sea level below. I guess all this turmoil got to me. As I was putting on my dry suit the constricting latex seal that goes around your neck must have hit hard enough on my gag reflex and out came my granola bar I had just eaten in attempts to settle my stomach. Once in the water I was fine. I guess personally floating along in the water is a different experience than being tossed around on a boat.
If I had the chance I'd definitely go back to the Channel Islands. There is a lot of potential there, although finding anything might be a large endeavor. But merely scanning the bottom while diving might prove to be useful. Side-scanning sonar was used in the area and up to 70 anomalies were recorded, but these were at deeper levels. The problem might be that with the size of ship required to get to the islands, this type of vessel can't easily troll around the island in waters were bottom levels aren't consistent with rock reefs poking up periodically. With such shallow depths however, bottom times with tanks should be fairly good. If one were to stay at or above 30 feet the bottom time would only be dictated by the amount of air in the tank and how quickly it is used. If an experienced diver spends their time at a shallow depth around the island, the dive time might be as much as an hour and a half to two hours. However, if more work is done than just hovering, for instance "digging" or fanning soil away to get at deeper levels, air will be consumed more rapidly. So with initial surveys, simple scanning of the environment might be the best way to go to maximize bottom time while covering a larger surface area.
If I were ever running an underwater project bent on looking for prehistoric remains, that's what I might do. Leave the toys on deck until you know you need them.
